High-temperature heating system



A ril 6, 192a. I 1,579,314

' B. S. HARRISON HIGH TEMPERATURE HEATiNG SYSTEM Filed Feb. 25, 1920 Pressure fiqgulafar gyms Patented Apr. 6,- 1926.

UNITED STATES PATENT OFFICE.

BURT S. HARRISON, OF BROOKLYN NEW YORK, ASSIGNOR TO CLARRIER ENGINEERING CORPORATION, OF NEW YORK, N. Y.

HIGH-TEMPERATURE HEATING I SYSTEM.

Application filed February 25, 1920. Serial No. 361,825.

To all whom it may concern:

Be it known that I, BURT S. HARRISON, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement Heating Systems, of which the following is a specification.

In the high temperature heating systems heretofore used for various commercial processes, such for example as heating japanning ovens and high temperature varnish ovens, etc., which require temperatures from about 300 F. to 600 F. or higher, the heat has been supplied in the following different ways; (1) by direct fires from oil or gaseous fuel; (2) by direct radiation, using oil or superheated steam at the required high temperature, or electricity; (3) by indirect radiation, supplying air by a fan at the required temperature to the oven, the air being heated either by means of steam or oil at high temperatures, or by means of air tube heaters in which the tubes through Erhich the air flows are heated directly by All of these systems are under certain conditions open to objections. Systems of the first classare inefficient, do not give an even distribution of heat and are expensive to operate. They are also extremely dangerous on account of the liability to explosions due to the exposed fire.

The second class is also ineflicient, expensive and highly dangerous. All direct radiation. systems are ineflicient as compared with indirect radiation systems in which heat is supplied by convection in a current of recirculated air, because the direct radiation surfaces are always on. the walls, or floor of the oven or both, the heat radiating into the center of the oven and against the outside walls, consequently, the tran'smis sion or radiation losses are proportional -to the difference between the temperature of the steam or oil and the outside air temperature. The center of the oven is lower in temperature than the outer zones nearer the coils, and in order to holda particular temperature say 400 F. at the center, it is necessary to carry a much higher temperature, about 500 F. at or near the coils, with 550 to 600 F. superheated steam or oil in the :oils. Not only are the transmission losses high in consequence, but the heating'of part in High-Temperature.

of the oven from 400 to 500 F. means a loss of fuel. In the case of indirect heating the temperature of the insides surfaces of the outer walls is usually less than the temperature in the center of the oven and the transmission losses are proportional to the difference between the oven tem- I perature and the outside an temperature Air admitted at say 500 F. and properly circulated will hold fully 400 F. at the center of the oven with a slightly lower temperature at the outer walls. With direct radiation, leaks in the oven cause streaky temperature conditions which prevent the uniform results that are possible with air circulation under fan pressure, in which a leak simply means so much air lost and does not result in infiltration with consequent cooling. Leaks in the oil piping of oil systems are very dangerous and it is practically impossible to prevent them ex cept by using jointless, welded pipes, which greatly increase the cost of the'apparatus.

The third or indirectclass of systems is much better as to the distribution of the heat, but the steam and oil installations are dangerous. Theairtube heater is inexpensive and economical if it can be located near the ovens, but for long runs of ducts the radiation loss is great, due to the necessity for large size ducts to convey the air at substantially atmospheric pressure from the airheater to .the oven or place where the heated air is used.

The primary object of this invention is to produce an eflicient and economical high temperature heating system suitable for long distance transmission, advantages of any of the known high temperature heating systems with none of their disadvantages.

Another object is to provide means whereby thoperation of the system can be held uniform at any desired temperature; and

also to improve heating systems in the other which has all of the ably carbon dioxide (G0,), which has a greater density, than superheated steam or air and is non-oxidizmg and non-inflam-v mable, is circulated under pressure in a closed system, whch includes a heat absorber or coil in which the compressed gas is heated by a direct fire, a radiator or heating coil connected by supply and return mains to the absorber, a compresser for circulating the compressed gas through the system, and preferably suitable means for supplying the system with gas and regulating the pressure and temperature of the gas.

A represents the heat absorber, B the radiator or heating coil which is connected to the absorber by supply and return flow mains C and D respectively, and E the compresser, preferably of the centrifugal or turbine type, which circulates the gas preferably at a pressure of about pounds gage through the absorber and radiator. The absorber A preferably consists of one or more pipe coils or a series of connected tubes ar ranged in a furnace 10 over a fire. In the preferred arrangement shown, the gas enters the top tubes of the absorber and is then passed through the next lower ones, etc.. so that it passes through the lowest and hottest tubes last. This materially increases the efficiency of the absorber. The fuel used for heating the absorber can be of any suitable character, but is preferably fuel oil or gas supplied by a pipe 11 to a burner 12. The radiator B can be of any suitable construction adapted for either direct radiation or indirect radiaton, in which latter case the radiator is arranged to heat air blown over it through a suitable chamber or duct by a fan.

F is a drum or holder containing the car bon dioxide under pressure. The system is filled with gas from this drum by closing a hand valve 13 in the main D and openinga relief valve 14 until the air is driven out of the system. Then the relief valve is closed. When the system has been filled with gas at about 40 pounds gage pressure, the valve 13 is opened and the system is ready for operation and can be started by simply starting the compresser and lighting the fire under the absorber. When the absorber A is heated to 600 F. or thereabouts, the gas pressure in the system rises to 100 pounds gage, which is the preferred operating pressure, although the gas can be used at other desired temperatures and pressures.

In order to enable the operation of the system to be held uniform at any desired temperature, the system is preferably equipped with a pressure-reducing valve or regulator 15, to control the pressure at which the gas is supplied from the holder F to the circulating system, and with a thermostat l6 affected by the delivery temperature of the gas in the main C and controlling the supply of fuel to the burner 12, or otherwise regulating the temperature in the absorber furnace. The pressure regulator 15 can be of any usual or suitable kind adapted to maintain the required pressure in the system. This regulator simply holds the system under the full predetermined pressure so that the density of the gas, and consequently its heat carrying capacity, do not decrease. This regulator can be set for 40 pounds gage pressure, for example, and each night when the system cools down, it will deliver gas to the system to make up any loss in pressure entailed during the days run. Or the regulator 15 could, if desired, be set for say 100 pounds gage pressure to work on the system when up to the operating temperature. In this case a thermostatic or other suitable valve 17 is preferably provided ahead of the pressure regulator to operate when the system is not up to temperature, to shut off the gas and prevent the system from filling up to 100 pounds pressure when cold. This valve 17 can be operated, for instance, under the control of the thermostat 16 which controls the temperature in the absorber furnace. In this case the valve 17 would be closed by its spring when the thermostatic system is not operating, the valve opening with increases in temperature of the gas in main C. The thermostat 16 is set for the desired delivery temperature of the gas in the main C and maintains this temperature through the medium of any suitable instrumentalities, such as a diaphragm valve 18 in the burner supply pipe 11 actuated by compressed air under the control of the thermostat.

19 represents a hand valve which is preferably provided between the circulating system and the thermostatic valve 17. The valve 19 is adapted to be closed to preventthe loss of gas from the circulating system whenever this may be necessary, as for example when making repairs to valve 17, replacing CO drum, F, or for any other reason.

The heating system above described has various advantages among which the following ma be mentioned:

The ieat carrying capacity of the carbon dioxide is about fifty percent greater than that of superheated steam at the same pressure and temperature. The heat transmission rate is higher than with superheated steam. Carbon dioxide at 100 pounds pres- Sure'and a temperature of about 639 F. has a density practically four times its density at atmospheric pressure and temperature. With four times the density it is only necessary to circulate one-fourth of the volume of the gas, and mains of one half the size can be used for the same velocity. With the gas compressed to 100 pounds gage pressure, the friction load (maintained resistance) on the system is only a few pounds per square inch. To carry the same heat with air the mains would have to be several times the size required for the compressed carbon dioxide, with the consequent great a density greater than air,

than are practicable with oil.

aeraaia friction and heat transmission losses, which are proportional to the ex osed surfaces of the ducts. The carbon dioxide will not freeze, and since it is non-oxidizing it will not form rust and scale and 010 the system, While with most gases, the oxi izing effects are very rapid at high temperatures. In starting up the system there, is no trouble with condensation or air, and no water hammer, as in the case of superheated steam. N o traps or air valves are necessary, and no by-pass, regulating flow valves, expansion tanks or other auxiliary apparatus, such as required in oil systems, are necessary. In case of a break in the system over thefire, instead of setting the place on fire, as would happen with oil, the carbon dioxide will dampen the fire. As the gas is not inflammable, there is no fire risk. The gas can be used safely at temperatures much higher Since it is not safe to heat oil above its flash point, which is about 600 F., in the case of a well known oil largely used for this kind of work.

I claim as my invention:

1. The hereindescribed method of high temperature heating which consists in confining a dry, non-oxidizing gas at a pressure above atmospheric pressure so as to circulate in a closed circuit, said gas having heating said gas in one portion of said circuit to raise the temperature of the gas, and causing the circulation of the heated gas through said closed circuit whereby the heat of the heated gas is utilized in another portion of said circuit. v

2. The hereindescribed method of high temperature heating which consists in confining a dry, non-oxidizing gas at a pressure above atmospheric pressure so as to circulate in a closed circuit, said gas having a density greater than air, heating said gas, in one portion of said circuit to raise the temperature ofthe gas,causing the circulation of the heated gas through said closed circuit whereby the heat of the heated gas is utifining a dry, non-oxidizing gas at a pressure lized in another portion of said clrcuit, and maintaining a substantially uniform pressure of the gas in said closed circuit.

3. The hereindescribed method of high temperature heating which consists in conabove atmospheric pressure so as to circuform dlOXl e leavm late in a closed circuit, said gas having a density greater than air, heating said gas in one portion of said circuit to raise the temperature of the gas, causing the circulation of the heated gas through said closed circuit whereby the heat of the heated gas is utilized in another portion of said circuit, and maintaining a substantially uniform pressure and temperature of the gas leaving the portion of the circuit where the gas is heated. V v

4. The hereindescribed method of high temperature heating which consists in circulatin carbon dioxide at a pressure above atmosp eric pressure in a closed circulating system including a heat absorber and a heat radiator, and heatin the carbon dioxide in the absorber to the esired heating temperature.

5. The hereindescribed method of high temperature heating which consists in circulating carbon dioxide at a pressure above atmospheric ressure in a closed circulating system inclu ing a heat absorber and a-heat radiator, and heating said absorber by the direct application of .heat thereto to raise the carbon dioxide to the desired temperature.

6. The hereindescribed method of high temperature heating which consists in confining carbon dioxide at apressure above atmospheric pressure so as to circulate in a closed circuit, heating the carbon dioxide in one portion of said circuit to raise the temperature of the carbon dioxide, causing the circulation of the heated carbon dioxide through said closed circuit whereby the heat of the heated carbon dioxide is utilized in another portion of said circuit, and maintaining a substantially uniform pressure of said carbon dioxide 1n said closed circuit.

7. The hereindescribed method of high temperature heating which consists in circulating carbon dioxide at a pressure above atmospheric ressure in a closed circulating system inclu ing a heat absorber and a heat radiator, heating said absorber to raise the carbon dioxide to the desired temperature, and maintaining a substantially uni ressure and temperature of the carbon the absorber. Witness my and this 20th day of February, 1920.

BURT S. HARRISON. 

